| 摘要 |
PROBLEM TO BE SOLVED: To move an apparatus driven by an ultrasonic motor accurately to a given position by stopping the drive of the ultrasonic motor and the count of rotation pulse signals if the monitored voltage applied by a given power supply becomes equal to a second prescribed threshold or lower. SOLUTION: If the voltage which a battery power supply 31 outputs becomes equal to a first prescribed threshold or larger, an ultrasonic motor 10 is driven and rotation pulse signals are counted. If it becomes equal to a second prescribed threshold or lower, the drive of the ultrasonic motor 10 and the count of the rotation pulse signals are stopped. This makes it possible to move a given apparatus accurately to a given position even if the output voltage of the battery power supply 31 becomes unstable and thereby the rotation pulse signal are disturbed. Furthermore, because the first threshold is set to a higher level than the second one, it makes it possible top move the given apparatus more accurately to the given position. |
